In hot air furnaces, it is customary to use a furnace which is located on the lower level of the dwelling or building such that the hot air from the furnace is permitted to rise, while the cold air is typically returned in a cold air return system to the furnace through cold air return ducts. In order to expedite the transfer of heated air throughout the building, it is customary to use a system of one or more fans in conjunction with the furnace. This is a relatively expensive approach, particularly in view of the increasing cost of electric power, and further represents a substantial cost addition to the furnace in its initial construction, installation and servicing.
The present invention relates to a unit in which ambient air is taken from about the furnace or from an intake connected to ambient air outside the building. The air is permitted to rise through the tubes or conduits which are arranged in a spaced array in the furnace. Air is taken in at the bottoms of the tubes at substantially ambient temperature, exhausted upwardly through the tubes and, responsive to the heating effect of exiting hot gas in the primary combustion chamber, the rapid flow upwardly of elevated temperature air through the conduits occurs. In this manner, there is provided a rapid and efficient gas to gas heat transfer.
In one embodiment of the invention, the tubes have their upper ends communicating with a hot air exit pipe formed at the top of the furnace shell. Thus, there is a lateral flow not only of the hot air leaving the primary combustion chamber but also a more important flow of hot air exiting from each open upper end of the several conduits. The lateral flow of heated gases and smoke mixed with noxious gases from the primary combustion chamber passes through the conduit interstices with a final passage outwardly through an exiting exhaust pipe. This pipe communicates with a chimney or other elevated outlet to provide for eliminating the gas and smoke from the building or dwelling itself.
In an alternate embodiment of the invention, certain of the basic elements just described in connection with the furnace are incorporated in a separate enclosure which is then joined in the hot air exhaust line of a separate combustion chamber such as, for example, that from a space heater or from a fireplace of the conventional type. The basic operation of the unit with respect to the separate enclosure unit is substantially as just described for the furnace embodiment in that there is provided a lateral flow of smoke and noxious gases which then goes to the exit or smoke pipe, while at the same time there is provided flow through a large number of separate vertically spaced conduits in a vertical direction so that the greatest possible amount of heat is conveyed not only by radiation from the primary combustion unit itself, but through the gases which are drawn from ambient, passed upwardly, finally emerging in the heated condition.
Other systems are known to the prior art in which heat transfer is provided through separate hot air chutes or separate tubes in such manner as to in various ways pass heat gas-to-gas to improve the efficiency of the heating unit. One example of this general class of system is shown in Stookey U.S. Pat. No. 3,129,931 issued on Apr. 21, 1964 for "Recuperator". The recuperator disclosed in that patent shows a system for effecting heat exchange between two gaseous media, but the basic system of Applicant and the incorporation of such a system in connection with a furnace, fireplace or the like in the manner in which the combination of Applicant operates is not shown.
The use of vertical or inclined tubes in heating systems has been shown generally in the following patents: Miller et al U.S. Pat. No. 3,223,078 issued Dec. 14, 1965 for "Warm Air Furnace" and Bassett et al U.S. Pat. No. 2,283,407 issued May 19, 1942 for "Heater".
The prior art, including the aforementioned patents, does not teach or make possible a heating system such as that of Applicant in which there is eliminated the need for fans and forced air circulation, but rather which operates on a gravity basis, amplifying the efficiency of standard hot air furnace of the gravity type by providing the conduit arrangement and enclosure positioned, constructed and connected in the manner taught by Applicant.